Electroplating, a metal finishing process, involves depositing a thin layer onto the surface, which is known as the substrate. It is also known as electrodeposition as it uses an electric current to achieve the desired reaction. Electroplating is used for metal finishing in many industrial applications.
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The first step in electroplating is the preparation of the substrate before the plating process. It involves cleaning the material to be electroplated in order to enhance the surface and make it more receptive to the metal coating.
The preparation of the metal substrate for plating is called electrocleaning, a technique that requires the connection of the substrate to an electrical lead attached to a rectifier. The substrate is then immersed in a chemical solution such as an alkaline solution. An electrochemical reaction will take place once an electrical current is introduced. The electrochemical reaction will stimulate the cleaning process. Electrocleaning can be used in barrel plating or rack plating applications.
The effectiveness of the electrocleaning job depends largely on the match between the base metal and the cleaning solution. The use of the wrong solution could result in the oxidation of the base metal. It could render the substrate chemically inert and prevent adhesion of the metal coating during the electroplating process.
The most commonly used solutions for electrocleaning include the following:
- Acid cleaners are generally used for magnesium and similar metals.
- Standard alkaline cleaners are best for steel, steel alloys, nickel, nickel alloys, copper, titanium and lead.
- Inhibited alkaline cleaners can be used with brass, tin, zinc, aluminum, aluminum alloys and bronze.
Electrocleaning can remove debris and dirt, such as paint, grease, oil, rust, and wax, from the metal substrate. There should be no water breaks during the rinsing process. Wiping the surface of the substrate using a sponge or a clean towel will expose any remaining dirt. If the process was effective, you should be able to inspect the material and see a uniform finish.